China will overtake the US as the world's biggest crude oil importer by 2017 as Chinese motorists drive domestic oil demand higher, consultancy Wood Mackenzie said on Tuesday.

China is on track to spend $500 billion on crude oil imports by 2020, far outstripping the peak cost ever incurred by the United States on crude imports of $335 billion, Wood Mackenzie said in a report.

It forecasts the U.S. crude oil import bill will fall to around $160 billion by 2020 as U.S. tight oil output from shale resources replaces imports from the Middle East and Africa.

"China will surpass U.S. demand for oil imports and peak spend," William Durbin, Wood Mackenzie's Beijing-based president of global markets, said in a statement.

The consultancy said the turning point for Chinese crude imports to surpass U.S. imports would be around 2017.

It forecasts China's oil imports will rise to 9.2 million barrels per day (bpd) by 2020 from 2.5 million bpd in 2005. U.S. oil imports, meanwhile, will fall to 6.8 million bpd from a peak of 10.1 million bpd.

"It means the United States is becoming more North America-centric for its supply needs and China more dependent on Middle East and Opec crude," Durbin said.

"We will therefore see Opec suppliers, who traditionally focused on the United States for crude sales, compelled to shift their focus towards China."

Between 2005 and 2020, Opec's share of Chinese oil imports is expected to rise to 66 percent from 52 percent.

"China will look towards Opec supply more as the United States relies on it less," Durbin said. – Reuters